Democrats have long had the MA program in their sights, arguing it undermines the traditional fee-for-service Medicare system by overpaying private plans. President Obama's healthcare reform law cut the program by more than $200 billion over 10 years.

"We cannot afford to overpay health plans in Medicare any more than working families and businesses can," Rep. Henry Waxman (Calif.), the top Democrat on the Energy and Commerce Committee, said in a statement. "The [health reform law] will eliminate many of the overpayments in Medicare Advantage plans over time, but as this report shows, there is more to be done."

"There is widespread agreement among policymakers and stakeholders that our health care system needs to move beyond the outdated fee-for-service (FFS) system to one that rewards quality, value, and better health outcomes," said spokesman Robert Zirkelbach. "Unlike the FFS part of Medicare, Medicare Advantage plans work to identify and address beneficiaries' specific health care needs through integrated care coordination, disease management, and quality improvement initiatives.

"Recent research has found that these programs are improving the quality of care for seniors in Medicare Advantage compared to FFS. For example, a report in the latest edition of Health Affairs found that seniors with diabetes in a Medicare Advantage special-needs plan had more primary care physician office visits and fewer preventable hospital admissions and readmissions than beneficiaries in FFS. Conclusions about whether the MA payment system appropriately pays plans should therefore not be based on GAO’s analysis."